Dehydrator cartridge



Feb. 15, 1955 A. E. ENGELDER 2,702,089

DEHYDRATOR CARTRIDGE Filed May 4, 1951 nited States Patent g DEHYDRATOR CARTRIDGE Arthur E. Engelder, Morenci, Ariz.

Application May 4, 1951, Serial No. 224,464

6 Claims. (Cl. 1ss-4.s

This invention relates to dehydrators generally and in particular to a dehydrator cartridge adapted for use in closed circuit metabolism or anesthesia equ pment. In its most simplified form a typical closed circuit anesthesia apparatus comprises the anesthesia machine proper, the face mask adapted to cover the oral and nasal areas of the patients face with a leak-proof seal, and two tubes leading from the anesthesia machine to the face mask, one tube being adapted to convey the anesthetic from the machine proper to the patients nose and mouth under the mask, and the other being adapted to return the exhaled air from the mask to the machine. The humidlty of the circulating gases contained in closed circuit anesthesia machines and metabolism instruments gradually rises due to introduction of water vapor in the circuit. This water vapor originates in the patients lungs and on each exhalation of the lungs is released to the circuit. In conventional machines no means are provided 'to remove water vapor, and thehumidity of the circulating gas increases with each exhalation.

In closed circuit anesthesia equipment the accumulation of water vapor in the system invariably leads to the condensation of moisture at critical points in the circuit. .This becomes quite troublesome, particularly when the moisture condenses on the transparent face mask as a fog and obscures the anesthetists view of the patients lips and nose. A prime object of this invention is to provide a simple means to prevent this undesired accumulation of water vapor. a

The device constructed in accordance with a preferred form of the present invention comprises acartridge provided with a suitable dehydrating substance. The cartridge is exteriorly smooth and preferably cylindrical and so adapted to fit into the tube conveying exhaled air from the patient to the'anesthesia machine proper. Also, if desired, a second cartridge may be fitted into the tube which conveys anesthetic from the machine to the patient. It is, accordingly, an object of this invention to provide a simple dehydrator cartridge adapted to be positioned in closed circuit anesthesia machines to remove water vapor from the anesthesia circuit.

A further object of the invention is to prevent the accumulation of water vapor in a closed circuit anesthesia machine from reaching the saturation point of the anesthetic in the vicinity of the face mask.

Still a further object of the invention is to prevent the formation of fog on the transparent face mask of a closed circuit anesthesia machine by limiting the content of water vapor in the anesthetic below the latters saturation point.

Another object of the invention is to provide a simple dehydrator cartridge for metabolism instruments, respirators and others in which water vapor accumulates.

A further object of the invention is to prevent the accumulation of water vapor in the closed circuits of .metabolism machines, respirators and others in which water vapor accumulates during use from reaching the saturation point of the gas conveyed in said circuits.

A further object of this invention is to provide an integral means in the circuit of a closed circuit anesthesia machine which will remove moisture from the circuit with a minimum of interference to the free flow of gas or air inthe circuit.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

Figure l is a view of a conventional anesthesia setup in 2,702,089 l atented Feb. 15, 1955 2 which a cartridge constructed in accordance with the present invention is positioned in the tube conveying exhaled air from the patients mask to the machine;

Figure 2 is an isometric view of a preferred embodiment of a dehydrator cartridge constructed in accordance with the present invention;

Figure 3 is a broken longitudinal section through the 1gartridge shown in Figure 2 taken on line 33 of that gure;

Figure 4 is a broken longitudinal section through a second preferred embodiment of the invention; 7

Figure 5 is the end view of a third preferred embodiment of the cartridge;

Figure 6 is the elevational view of the embodiment shown in Figure 5;

Figure 7 is a broken section taken upon the longitudinal axis of a fourth preferred embodiment and shows the cartridge positioned in a broken section of a tube;

Figure 8 is a transverse section through the fourth preferred embodiment taken on line 88 of Figure 7; an

Figure 9 is a partial section of the outlet or inlet of a conventional anesthesia machine adapted to receive and seat a cartridge constructed in accordance with the present invention.

Referring again to the drawing, and to Figure 1 in particular, a conventional closed circuit anesthesia setup is illustrated. The anesthesia machine proper is indicated by reference character 14, the face mask indicated generally by 11, the anesthetic conducting tube by 13, and the tube for exhaled air by the reference character 12.

The direction of fiow of anesthetic and exhaled air between machine 14 and mask 11 is indicated by the arrows adjacent the tube in which each is carried, the tubes conventionally being flexible and constructed of a suitable gas-impervious material such as rubber. A dehydrator cartridge constructed in accordance with' the present invention is indicated generally by reference character 21 in Figure l and is shown positioned in the tube 12 carrying the exhaled air. A second cartridge may, if desired, be similarly positioned in tube 13 for the anesthetic. The cartridge is so dimensioned that it can be forced into the tubes with a tight fit from one or the other ends. Alternatively, the tubes may be separable between their ends so that the cartridges can be inserted at the points of separation.

The dehydrator cartridge may be mounted in its carrying conduit right at the anesthesia machine itself when the latter is so constructed as to receive it. In a preferred construction of this type the machine is provided with projecting exteriorly threaded inlet and outlet pipes 16 and 17 for exhaled air and anesthetic,respectively. The two are identical, the inlet unit being shown in Figure 9. Connector tubes 18 and 19 seat upon the inlet and outlet pipes, being formed with interiorly threaded inner ends adapted to seat in gas-tight relationship thereon. Centrally each connector tube is formed with a chamber 20 sized as to seat a cartridge 21 with a close fit and clamp it against the end of the adjacent pipe which may be suitably recessed to receive it.

The outside surface of the cartridge and the inside surface of the tubes 18 and 19 should be smoothly finished in order that the cartridges may be inserted and replaced easily. The outer ends of tubes 18 and 19 may be corrugated, as shown, so that the flexible conducting tubes may readily seat thereon.

A dehydrator cartridge constructed in accordance with the present invention can be adapted for use with an oxygen tent by simply increasing its capacity, that is, its diameter and length, and making it insertable in the oxygen inlet port or outlet port, or both, of the oxygen tent.

Referring now to Figures 2 and 3, a preferred embodiment of the dehydrator cartridge 21 is illustrated and is seen to comprise a cylindrical body 22 within which is positioned a dehydrating substance 28. Body 22 is formed with a closure wall at one end, its opposite open end being closed by a removable cap 24. The cap is suitably held in place, and in a preferred form the end of the casing is interiorly threaded at 26 and receives the threaded reduced diameter body of the cap. The

c os nd of ea in 2 is P rfo t d a n p 2 "is similarly perforated as indicated at 29. The perforations 27 and 29 are sufiiciently small as to retain the dehydrating or hygroscopic material without loss but their are i u i t t n re th t the fl w of s or air will "not-beimpeded. With the cartridge positioned in a tube carrying anesthetic gas or air the latter passes-lon- 'gitudinally through the casing 22 and through the ports 27 and 29 in either direction. In so doing it passes in intimate contact with the hygroscopic material 28 which functions to absorb the water vapor carried thereby.

Referring to Figure '4, a second preferred embodiment of the invention is illustrated. The dehydrator cartridge, indicated generally by reference character 21A, comprises an open-ended cylindrical body 31 containing a dehydrating substance 28, preferably crystalline. One end of body 31 is interiorly threaded at 3210 receive an exteriorly threaded ring cap 33 across the interiorly grooved outer end 37 of which extends a wire gauze screen 36. A resilient ring spring 34 snapped 'in the groove and against the peripheral margin of the screen retains it in the ca A circular groove 38 is formed in the-interior of 130 y 31 near its unthreaded end and a 'wiregauze screen 36 is seated in the groove 38 by its retaining ring 34. In this construction the screen 36 takes the place of the erforations of the first embodiment and serves to retain the hygroscopic material while Figures 7 and 8 are illustrative of a fourth preferred embodiment of the present invention. The cartridge is here indicated generally by reference character 51 and comprises two circular end plates 52, each having a circular continuous channel 54 constructed therein. Channel 54 is adapted to function as the seat of a pair of concentric wire gauze cylinders 56 and 58 and to retain them is spaced relationship, the end portion of inner cylinder 56 encircling the inner wall .of the channel while the end portion of the outer cylinder 58 is enclosed by the channels outerwall.

The peripheral wall of each circular end plate 52 abuts V the interior of exhaled-air-conducting tube 12 as shown.

offering slight resistance to the movement of gas therethrough.

Commercial anhydrous calcium chloride, a granular mass comprising a mixture of calcium chloride and calcium chloride monohydrate, is entirely suitable for use in the embodiment of the invention described. In the course of the exposure of this agent to water vapor the dihydrate, the tetrahydrate, and finally the hexahydrate (referred to in the order of their water vapor pressures) are formed as water is absorbed. Further exposure produces a solution of calcium chloride, obviously a stage :to be avoided in practice. A cartridge packed with the aforementioned dehydrating substance will exhibit the various stages of hydration beginning with the hexahydrate where the gas enters the cartridge and graduating through the lesser hydrated phases to the zone of exit. As long as the major portion of the column appears dry the final state of solution is remote. When it appears, however, that half or more of the column is wet, or damp, the cartridge must be removed. After removal it may be discarded, or it may be heated in an oven, whereupon water is driven off. In all events the cartridge should never be reversed in the anesthesia. tube on the mistaken theory that by presenting the dry'end to the incoming gases and the moist end to the outgoing gases that the. original effectiveness of the cartridge in the circuit will be restored.' Actually, under these conditions the humidity of the issuing gases will be raised to the :Water vapor pressure of the highly hydrated phase, regardless of how eflicient the lesser hydrated compounds :may be in absorbingmoisture, the completeness of gas :dehydration being inversely proportional to water vapor pressure of .the last hydrated'phase passed through only.

Figures 5 and 6 are illustrative of a third preferred embodiment of the present invention. In this form the dehydrator cartridge, indicated generally by reference character 41, comprises two circular end plates 42, each formed centrally with a'bore or seat 44 and each adapted :to receive one end of a wire gauze cylinder 43. The cylinder may be constructed of wire gauze or other suitably perforated material filled with dehydratingmaterial. Two arcuate elongated ports 46 are-formed in each plate 42 exterior circumferentially outside the seat H 44. A plurality of connecting spacing pins '47 extend between the end plates 42 at the sides of the cylinder 43 and cooperate with the latter in fixing them in spaced relationship. With the unit positioned in a gas or air conduit, the end plates closely fitting therein, the anesfl'EtICQPfiXhfilGd air passes through ports 46 in one plate and along the exterior surface of wire gauze cylinder .43, the water being drawn from the passing gas by the absorbing effect of the dehydrating agent contained in the. cylinder. The gas then passes :through the elongated arcuate ports 46in the other end plate and on through the anesthesia circuit. Hart of the gas or air will enter the forwardend of the cartridge and traveitherethroug'h, e forward :end being exposed ;directly:tov the :flow, as is seen in Figure 5.

Ports 59 are present in both end plates 52 being spaced uniformly around the channel 54, and a central port 57 is located within that channel. In this embodiment the dehydrating agent 28 is positioned in the chamber formed by the perforated inner cylinder 56, outer cylinder 58 and the end members 52. These cylinders may be constructed of wire gauze or other suitable perforated material. The end plates and cylinders are held together as a unit by two or more longitudinally extending headed pins 61 which extend parallel to the cylinders and at their sides. The heads on the pins, being positioned adjacent the outer faces of the end plates, positively prevent separation and hold the plates in abutting relation to the cylinder ends. In the use of this, the fourth embodiment of the invention, anesthetic gas or exhaled air passes through holes 59 in one plate 52, over and along the exterior surface of outer wire gauze hollow cylinder 58, and exits from the cartridge at its other end from the ports 59. A parallel flow takes place inside inner eylinder 56, this how entering through one port 57, traveling the length of cylinder 56, and making its escapethrough the port at the opposite end of the unit. The water is drawn from the passing gas through the exterior and interior side walls by the absorbing effect of the dehydrating agentcontained between the cylinder walls. v

If preferred, layers ofloosely woven fabric, indicated generallyby reference character 53, may be positioned over the exterior perforated surface of inner gauze cylinder 56 and over the interior surface of outer gauze cylinder -58 to prevent the finely particulated material from leaking through the perforations of said material.

The cylinders'56 and 58 may be formed of material other than wire gauze, it being requisite that the necessary strength-be present to retain the hygroscopic material enclosed and, additionally, that there be a minimum ofinterference with the ability of that material to absorb moisture from the passing gas or air.

The embodiments of the dehydrating cartridge illustrated in Figures 5, 6,7 and 8 are better adapted to the :use of'more finely grained dehydrating agents that the embodiments of FiguresZ to .4, inclusive. Examples of these agents are alumina (A1203) and heat-treated calcium chloride, both of which should be lightly packed in the dehydrator cartridge. Glass, metal or ceramic construction is preferred for the dehydrator cartridge body in order that following use the cartridge may be oven dried and reused. Plastic cartridges should be of the disposable type.

In the use of a dehydrator .cartridge constructed in accordance -With the present invention the connecting tube .12 for exhaled air is removed from the exhaled :air inlet 16 of aconventional anesthesia machine and the cartridge 21 is inserted in the connecting tube. The latter is then connected to the exhaled air inlet of the machine. Alternatively, exteriorly corrugated metallic -connector tubes 18 and 19 are present between the end of the conducting tubes and'the anesthesia machine. These may be unscrewed from their threaded seats 16 and 17 upon the machine and the dehydrator cartridge inserted therein, as described. A dehydrator cartridge may be used in the anesthetic outlet of the conventional machine as Well as in the exhaled air inlet if the amount of moisure in the circuit requires the use of two cartridges to remove it. If two cartridges are used it is advisable that means be included in the anesthesia machine to propel the gas in the circuit.

if desired an indicator may be mixed with the dehydrating agent to show when the agent has exhausted its dehydrating power. A small amount of cobalt chloride will serve this purpose. As the dehydrating agent becomes moist it will then turn from blue to red in color. Baking in the oven will cause a reverse change in color of the indicator as the moisture is removed from the dehydrating agent.

While the particular apparatus herein shown and described in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

I claim:

1. In a dehydrator cartridge of the class described, a first large diameter hollow cylinder and a second small diameter hollow cylinder, said cylinders being open at their opposite ends and having air-permeable side walls, a pair of circular end plates of larger diameter than said large diameter cylinders and having smoothly surfaced peripheral walls adapted to be received in the connecting tube of a closed circuit anesthesia machine, a circular channel in one side of each of said end plates, the outer wall of each channel abutting an end portion of said large cylinder and the inner wall abutting an end portion of said small cylinder, said cylinders being held in spaced concentric relationship by said end plates, and a plurality of rigid pins extended parallel to the axes of said cylinders exteriorly of said large cylinder to fixedly space said end plates, each of said end plates being formed with a plurality of air ports arranged to admit and direct exhaled air or anesthetic over the exterior surface of said large cylinder and inside the encircling wall of the supporting connecting tube, and each of said end plates being formed with a central port adapted to admit and direct exhaled air or anesthetic through the interior of said small cylinder, said cylinders being adapted to contain a conventional grannular dehydrating agent between their respective side walls.

2. In a dehydrator cartridge of the class described, a pair of hollow cylinders open at their ends and having permeable side walls, said cylinders being positioned in spaced concentric relation and containing a dehydrating agent between their respective side walls, a pair of circular supporting members positioned at opposite ends of said cylinders and of greater diameter than the larger of said cylinders, each of said supporting members being formed with a circular channel the outer wall of which seats the outer cylinder and the inner wall of which seats the inner cylinder, and ports in said end plates located exteriorly and interiorly of said cylinders and adapted respectively to admit and direct air or gas over the exterior surface of said outer cylinder and admit and direct air or gas over the interior surface of said inner cylinder when said cartridge is positioned in an air or gas conduit with said supporting members closely enclosed thereby.

3. In a dehydrator cartridge adapted to be enclosed in a gas-conducting conduit, a pair of spaced circular end members adapted to fit within said enclosing conduit, each of said end members being formed with transverse openings through which a gas traversing said enclosing conduit may pass, each of said end members also being formed on its side facing the other end member with a seat for the end of a cylinder, a foraminous cylinder containing granular hygroscopic material extended between said end members and supported by said seats, said cylinder being of smaller diameter than said end members certain of the openings in which are positioned as to direct a gas passing through said en closing conduit along the exterior surface of said cylinder, and retaining means to prevent the separation of said end members.

4. A dehydrator cartridge of the type adapted to be enclosed in a gas-conducting conduit, comprising a pair of spaced circular end members adapted to fit within said enclosing conduit, each of said end members being formed with transverse openings through which a gas traversing said conduit may pass, each of said end members also being provided on its side facing the other end member with means to mount the end of a cylinder, and a perforated cylinder containing granular hygroscopic material extended between said end members and supported thereby, said cylinder being of smaller diameter than said end members certain of the openings in which are positioned as to direct a gas passing through said conduit along the exterior surface of said cylinder.

5. In a dehydrator cartridge of the type adapted to,

be enclosed in a gas-conducting conduit, a pair of spaced circular end members adapted to fit within said conduit, each of said end'members being formed with transverse openings through which a gas traversing said conduit may pass, each of said end members also being formed on its side facing the other end member with a seat, a hollow open ended cylinder formed of spaced concentric foraminous walls and resting at its ends on said seats, the space between said walls being filled with granular hygroscopic material, said cylinder being of smaller external diameter than said end members, certain of the openings in said end members being positioned to direct a gas passing through said conduit along the exterior surface of said cylinder and others of the openings in said end members being positioned to direct said gas into the open end of said cylinder and along the inner wall thereof, and tie elements extending between said end members to prevent their separation.

6. In a dehydrator cartridge of the type adapted to be enclosed in a gas-conducting conduit, a pair of spaced circular end members adapted to fit within said conduit, each of said end members being formed with transverse openings through which a gas traversing said conduit may pass, each of said end members also being formed on its side facing the other end member with a circular channel, a hollow open ended cylinder formed of spaced concentric foraminous walls and resting at its ends in said channels, the space between said Walls being filled with granular hygroscopic material, said cylinder being of smaller external diameter than said end members, certain of the openings in said end members being positioned to direct a gas passing through said conduit along the exterior surface of said cylinder and others of the openings in said end members being positioned to direct said gas into the open end of said cylinder and along the inner wall thereof, and retaining elements comprising elongated pins extended between said end members to retain said members and said cylinder as a unitary construction.

References Cited in the file of this patent UNITED STATES PATENTS 1,794,940 Zimmerman Mar. 3, 1931 1,965,461 Gray July 3, 1934 2,001,828 Smith May 21, 1935 2,151,053 Solberg Mar. 21, 1939 2,103,144 Carre Dec. 21, 1947 2,478,715 Schmitt Aug. 9, 1949 2,507,028 Lockwood May 9, 1950 2,511,726 Lockwood June 13, 1950 2,556,292 Newcum June 12, 1951 2,593,132 Gannon Apr. 15, 1952 2,633,131 Crosvenor, Jr Mar. 31, 1953 FOREIGN PATENTS 228,837 Great Britain Feb. 12, 1925 233,773 Great Britain May 14, 1925 254,942 Great Britain July 15, 1926 

